Liquid crystal display televisions, monitors, cellular phones, or the like have been widely used in recent years as flat panel displays that are characterized by thinness, light weight, and the like in comparison with the conventional cathode-ray tube display. This type of liquid crystal display device is known to use as a panel display for a liquid crystal panel an active matrix substrate on which are arranged in a matrix pattern pixels that have picture element electrodes including a plurality of data wiring lines (source wiring) and a plurality of scan wiring lines (gate wiring) arranged in a matrix pattern, and switching elements such as thin film transistors (TFTs) arranged in the vicinity of the intersections of the data wiring lines and the scan wiring lines, the picture element electrodes being connected to these switching elements.
Moreover, addition of sufficient auxiliary capacitance and improvement of the aperture ratio are required in order to improve the display quality of the liquid crystal display device using the active matrix substrate configured in this manner.
On the conventional active matrix substrate as described, for example, in the below listed Patent Document 1, an auxiliary capacitor wiring formed from aluminum or an alloy layer mainly constituted by aluminum and an auxiliary capacitor electrode formed from a transparent electrically conductive film formed from indium tin oxide (ITO) or the like are connected together with a high melting point metal layer therebetween (formed from a high melting point material such as molybdenum or the like or an alloy thereof). In this conventional active matrix substrate, it has been possible to prevent dissolution of the auxiliary capacitor wiring line and reduction of the auxiliary capacitor electrode, caused by a development solution used during patterning of the auxiliary capacitor wiring lines, and to prevent the resulting deterioration of transparency of the auxiliary capacitor electrode and the accompanying great decrease of transmittance of the picture element.